4484 - IsTuple

[gasmg]

type ReadonlyTuple<T extends readonly any[]> = T extends readonly []
	? readonly []
	: T extends readonly [infer Head]
	? readonly [Head]
	: T extends readonly [infer Head, ...infer Tail]
	? readonly [Head, ...ReadonlyTuple<Tail>]
	: never;

type TupleOrReadonlyTuple<T extends readonly any[]> = "push" extends keyof T ? [...ReadonlyTuple<T>] : ReadonlyTuple<T>;

type IsTuple<T> = [T] extends [never]
	? false
	: T extends ReadonlyArray<any>
	? T extends TupleOrReadonlyTuple<T>
		? true
		: false
	: false;